This invention relates to a new and improved assembly for insertion of a catheter into a patient. More specifically, this invention relates to a stylet providing an axially aligned puncture tip, the stylet being inserted through a catheter to form an assembly which can effectively pierce a vein. Upon withdrawal of the stylet, the catheter remains in place in the vein.
Presently manufactured hypodermic needles, cannula, and other needles employ a ground needle tip having an off-axis alignment from the longitudinal needle axis. This enables a relatively even needle tip bevel to be formed. These off-axis tips present a problem in that insertion of the needle into the vein of a patient or user must be in an off-axis alignment mode, and this can lead to the needle double penetrating the wall of a vein. This is due to the inherent longer length of the needle tip beyond the catheter.
Another problem of employing a hollow needle with a catheter inserted therein is that upon insertion into a vein, there exists the possibility of the catheter double puncturing the vein.
Another problem associated in using a cannula or hypodermic needle is the necessity to manufacture the central bore of the needle, and in an accurate manner.
Another problem with prior art needles and cannula is that flashback of blood into the needle is not observed until the blood reaches the distal end or hub portion of the needle.
It would be preferable to provide an assembly including a catheter and vein piercing device such that flashback is observed almost immediately, i.e., near the puncture tip rather than at the distal end, or hub of the assembly.
It would be also preferred to form a puncture tip that not only has an even bevel, but in which the tip is axially aligned with the central longitudinal axis of the vein piercing device and the catheter. This longitudinal alignment reduces the possibility of double puncturing the vein.
Another problem with prior art needles is due to coring, and can result in blockage of a needle, or subsequent embolism in a vein, artery, etc. It would be preferred to manufacture a vein piercing device that does not require formation of a hollow bore, and thereby would eliminate the possibility of coring.
Furthermore, it would be desireable to manufacture a vein piercing assembly that minimizes or reduces the possibility of double puncturing a vein or artery by minimizing the amount of exposed puncturing tip in front of the catheter.
Present over-the-needle catheters have at least two problems: i. they have a proximal end shoulder, which makes it difficult to insert the catheter into a vein; and, ii. the catheters remain stiff when in place in the vein, and this causes patient trauma. It would be desireable to manufacture a vein piercing assembly in which the vein piercing element is adapted to easily pierce the vein and then be removed, leaving behind a soft associated catheter in the vein, with reduced trauma.